1. Field of the Invention
The invention relates generally to components for transformation of optical signals, and more specifically to an optical connector used to transmit optical signals coming from a number of input light transmitting channels fixed on one rotating platform to a number of output light transmitting channels fixed on another rotating platform without cross coupling between different output channels and without any other distortion of the transmitted optical information, as it is required for various military, industrial and medical applications.
2. Information Disclosure Statement
Multichannel laser beam delivery systems and optical communication systems based on transmission of information through a plurality of independent optical channels using, for example, optical fibers have found many important military, industrial and medical applications. For solution of many practically important problems it is required to have a tool for simultaneous and independent transmission of the optical signals coming from a number of input channels fixed on one rotating platform to a number of output optical channels fixed on another rotating platform without distortion of the transmitting signals. A typical example of such a problem is an optical connection through a rotary assembly of an input optical fiber bundle gathering optical signals from an array of optical fiber sensors detecting, for example, parameters of helicopter or turbine blades with an output optical fiber bundle on board the helicopter or stationary turbine platform. Other examples are gathering of amplitude information of optical signals coming from a rotating optical antenna, gathering of phase information of optical signals coming from rotating gyroscope or gathering information from optical fiber hydrophones distributed in ocean whose optical fiber cable is collected by a rotating roller on board a ship. Still another example is a medical laser delivery optical fiber bundle wherein it is required to keep optical connection between individual input and output fibers of the bundle during a medical procedure independent from rotation of a bundle tip.
Optical information coming from various sensors are usually coded either in amplitude or phase of optical wave carder. Therefore, it is extremely important to have means for optical connection between pluralities of optical fibers fixed on mutually rotating platforms which keeps both the amplitude and phase of the optical signals transmitting between corresponding fibers.
Numerous standard connectors designed for connecting optical fiber bundles can not be used to connect individual fibers of the bundle in such a way that each specific incoming optical fiber remains optically connected to each specific outgoing fiber independently on relative position of the input and the output platforms. Therefore, special connectors are to be designed to solve this problem. U.S. Pat. No. 5,392,370 describes a multichannel fiber optic rotatable interconnection system comprising step-index multimode optical fiber. The optical signals are transmitted by exciting different modes in this multimode fibers which are supposed to have minimum crosstalk. This connector, however, can not provide sufficiently good separation of different optical channels, since it is difficult to perform selective excitation and detection of modes in the multimode fiber having relatively small cross section. Even employing complicated optical systems for selective excitation and detection of different modes in the multimode fiber can not solve the problem of perfect matching of input/output optical fields to mode field configuration required for selective excitation and detection of specific fiber modes. This matching can be performed only by employing special optical means, for example, computer generated holograms. Moreover, in the case when multimode fibers are used for delivering input optical signals, a beam irradiated by each input fiber exhibits a complicated nonstationary speckle pattern resulting from interference of different fiber modes (modal noise). It is almost impossible to match this speckle pattern to a desired mode field configuration. Therefore, it is a practically important problem to provide a means for multichannel transmission of optical signals from arbitrary optical channels through a rotating interface without employing selective excitation and detection of specific modes in the optical fiber.